1. Field of the Invention
The present invention pertains to a pressure plate assembly for a friction clutch, the pressure plate assembly including a housing that is connectable to an abutment arrangement for rotation in common around an axis of rotation, a pressure plate, mounted in the housing and capable of rotating together with the housing around the axis of rotation, and an energy storage element mounted on an outside surface of the housing so that it exerts a force on actuating sections of the pressure plate which extend across the edge of the housing.
2. Description of the Related Art
In pressure plate assemblies that are used in, for example, multi-disk friction clutches in which several clutch disks are stacked axially in a row and the torque to be transmitted via the clutch is transmitted via these several clutch disks, the energy storage element, which is usually designed as a diaphragm spring or disk spring, can be mounted on the outside surface of the housing to make more efficient use of the available space. In the state before the pressure plate assembly has been connected to an abutment arrangement such as, for example, a flywheel or the like, there is no reactive force present to oppose the engaging force transmitted by the energy storage element to the pressure plate. As a result, the energy storage element will relax until, for example, it comes to rest against the radially outer area of the housing. The engaging force exerted on the housing can deform the housing, thereby creating difficulties when the attempt is made to connect the housing to the abutment arrangement.
This potential deformation state is shown in simplified fashion in FIG. 5, which shows the housing 12 of a pressure plate assembly 10. An energy storage element 22 (shown, for example, as a diaphragm spring in FIG. 5) is arranged on an outer axial side 14 of the housing 12 and is supported by several spacer pins 16 and by two wire rings 18, 20. In the state before the housing 12 has been connected to an abutment 24 (shown schematically) the radially outer area of the energy storage element 22 exerts an engaging force as it relaxes on the radially outer area 26 of the housing 12, with the result that these radially outer areas 26 of the housing 12 are deformed by the force feedback thus produced. The sections 28 by which the housing is attached to the abutment may also deformed or at least slightly tilted, which makes it much more difficult to perform the assembly work. If, despite these difficulties, the housing 12 is bolted to the abutment 24 in this state, the housing 12 can relax as soon as the clutch thus assembled is disengaged the first time, and this can have the result that the bolts used to connect the housing 12 to the abutment 24 are no longer firmly tightened and can proceed to loosen.